Protective system for electric apparatus



- 1,640,309 A g- 1927- M. BUCHHOLZ PROTECTIVE SYSTEM FOR ELECTRIC APPARATUS Filed April 16. 1925 flu m.

//7 yen for,

Max Buck/va/z iffy.

Patented Aug. 23, 1927.

UNITED STATES MAX BUCHHOLZ, F CASSEL, GERMANY.

PROTECTIVE SYSTEM FOR ELECTRIC APPARATUS.

Application filed April 16, 1925, Serial No.

My invention has reference to means for protectlng electric apparatus operating in an insulating medlum, such as 011 transformers, oil switches, grounding throttling coils,

resistances and the like, and it is one of the important objects of my invention to provide a device of very simple construction and great reliability and adapted to operate before extensive injuries to the apparatus to be protected can occur by sparking, overloading or other disturbances.

My invention is particularly based on the fact that in the case of disturbances in .the operation of the apparatus to be protected 1 or in the case of sparking or other irregularities of operation, or whenever such irregularities are imminent, as Well as in the case of any ebullition or fermentation processes in the oil, serving as an insuluating medium, bubbles of gases of decomposition are formed which can operate protective means, for instance an electric contact, either a working or a closed contact, which is adapted to switch out of circuit the apparatus to be protected, or which will operate an alarm or annunciator device indicating the disturbance, or which is adapted to effect both kinds of operations.

According to the present invention I uti- 80 lize the air or gas pressure arising above the level of the insulating medium in consequence of the generation of the gases or vapors for displacing some part, member or body closing an aperture in the vessel or container surrounding the electrical apparatus to be protected and the insulating medium, such part, member or body, when so displaced, being arranged for actuating a switch or an alarm or annunciator device either directly or by closing or opening a contact arranged for effecting such actuation.

In the drawings aflixed to this specification and forming part thereof, three devices embodying my invention are illustrated diagrammatically by way of example.

In the drawings Fig. 1 is an elevation partly in vertical section of a substantially mechanical device, while Figs. 2 and 3 are similar views of a device employing electric contact makers of a well known type.

Referring first to Flg. 1, m is a transformer vessel or casin containing a body n of oil and the trans ormer (not visible).

23,677, and in Germany February 5, 1923.

0 is a leading-in insulation for the conductors.

a is a tubular extension mounted on the cover of the vessel and b is a cap which closes this extension, without, however, being preventedfrom being displaced in vertical direction. p is a rod fixed on this cap and c isa double-armed pawl pivoted to the rod pat 1' and cooperating with another pawl d forming part of a contact device, oil

switch, alarm, annunciator device or the like arranged for cutting out the transformer or for becoming operative according to its character, whenever contact with pawl Obviously this will happen as soon as the pressure existing below the cap b exceeds a certain limit, that is as soon as the gases or vapors generated in consequence of unnormal operation of the apparatus to be protected have accumulated below the cover of the vessel m or in the tubular extension at to the extent of overcoming the counterpressure exerted by the cap b and the members connected with it.

In the modification disclosed in Fig. 2 the member to be displaced consists of a body 8 of mercury filling the bend of a U-shaped tube 6 mounted in the side wall of the container m below the liquid level. One terminal t of a protective circuit comprising an oil switch, alarm or the like extends into the bend of tube 8 so as to be in permanent contact with. the mercury. The other terminal a extends into the tube above the outer arm of the mercury body 8. Whenever the pressure above the liquid level rises, owing to the accumulation of gases or vapors of decomposition, the inner arm of the mercury will be acted upon by the liquid so as to be lowered, while the outer arm rising in the other tube will make contact with the terminal u, thereby cutting in the protective device.

The modification disclosed in Fig. 3 is identical with the one disclosed with reference to Fig. 2 in everything except for the fact that the tube e containing the mercury and the terminals, instead of being mounted below the level of and being in communication with the insulating liquid, is-mounted above the liquid level so that the gases or vapors accumulating below the cover of the container m will act on the mercury direct. The circuit to be controlled by the contacts referred to may excite either directly or by the medium of an intermediate relay thereleasing coil. of an oil switch which inawl c is moved out of terrupts the endangered circuit. In the case of apparatus the circuit of which does not include an oil switch, as freguently occurs, for instance in the cases 0 transformers mounted in the field at wide distances apart, other provisions should be made for the purposes of this invention.

Besides the form of construction herein shown and described, the invention is susceptible of a variety of other modifications and forms of application of the principle of my invention all of which operate substan be operatively influenced by such emanations, and connected to fuses or equivalent safety means, the instrumentalities shown and described in this specification as embodiments of these principles being susceptible of modifications without deviating from the spirit of my invention as set forth in the claims. I

In the claims the term gases is meant to comprise also vapors and fumes.

I claim 1. Protective system for insulated electric apparatus comprising a container and a supply of an insulating medium which is not volatile under normal conditions, surrounding the apparatus to be protected, a protective means and means adapted to be displaced bodily by the increase of pressure resulting from a decomposition of the insulaparatus and, when thu tion due to unnormal working of the aps displaced, to 'operate said protective means.

when thus displaced, to operate said protective means.

3. Protective system for insulated electric apparatus comprising a container and a supply of an insulating medium which is not volatile under normal conditions surrounding the apparatus to be protected, a protective circuit and means adapted to be displaced bodily by the increase of pressure resulting from a decomposition of the insulation due to unnormal working of the apparatus and, when thus displaced to operate said protective circuit.

4;. Protective systemfor oil insulated electric apparatus comprising a container and a sup" of oil which is not volatile under normal conditions surrounding the apparatus to be protected, a protective circuit and a mercury contact device communicating with the interior of said vessel and adapted, on the mercury being displaced bodily by the increase of pressure resulting from a decomposition of the oil due to unnormal working of the apparatus, to vary the operative condition of said circuit.

5. Protective system for insulated electric a paratus comprising a container and a supp y of an. insulating medium, which is not volatile under normal conditions, surrounding the apparatus to be protected, and a protective means adapted to be displaced bodily by the increase of pressure resulting from a decomposition ofvthe insulation due to unnormal working of the apparatus.

In testimony whereof I affix my signature.

. MAX BUCHI-IOLZ. 

